Supplementary Material for: Electroacupuncture Alleviates Obesity and Insulin Resistance via the GLP-1-VTA DA Reward Circuit

Objective: We investigated the effects of electroacupuncture (EA) on improving obesity and insulin resistance (IR) in high-fat-diet-induced (HFDI) obese rats by modulating the nucleus tractus solitarius (NTS) glucagon-like peptide-1 (GLP-1)-ventral tegmental area (VTA) dopamine (DA) neural reward circuit, thereby uncovering a possible central mechanism underlying EA’s actions in improving obesity and IR. Methods: We randomly allocated 45 Wistar male rats to five groups (normal, model, EA, chemogenetic activation, chemogenetic suppression + EA), with nine rats in each group. All interventions were conducted within 8 weeks after the model was established. We tested rats for obesity phenotypes included body mass, Lee's index, 24-h food intake, and glucose-metabolism parameters. We observed protein and gene expression for GLP-1 in the NTS and tyrosine hydroxylase (TH) in the VTA by western blotting (WB) and real-time polymerase chain reaction (RT-qPCR), as well as their localization by immunofluorescence. We also determined the DA content in the VTA using high-performance liquid chromatography (HPLC). Results: Obese rats exhibited marked hyperphagia, accompanied by increased excitability of DA neurons in the VTA region and reduced insulin sensitivity. After EA treatment, obese rats showed augmented excitability of NTS GLP-1 and suppression of VTADA neurons with a diminution in food intake, showing results similar to those in the chemogenetic-activation group. After EA treatment and while inhibiting GLP-1 neurons by chemogenetics, the effect of EA on activating GLP-1 neurons and inhibiting VTADA was partially abrogated. The effects of improving obesity and insulin sensitivity were likewise also suppressed. Conclusion: EA effectively activated GLP-1 neurons in the NTS, thereby inhibited the expression of DA in the VTA and improved obesity and insulin sensitivity in HFDI-obese rats.

研究目的：本研究探讨了电针（electroacupuncture, EA）通过调控孤束核（nucleus tractus solitarius, NTS）胰高血糖素样肽-1（glucagon-like peptide-1, GLP-1）-腹侧被盖区（ventral tegmental area, VTA）多巴胺（dopamine, DA）神经奖赏通路，改善高脂饮食诱导（high-fat-diet-induced, HFDI）肥胖大鼠的肥胖与胰岛素抵抗（insulin resistance, IR）的作用，以期揭示电针改善肥胖与IR的潜在中枢机制。
研究方法：我们将45只雄性Wistar大鼠随机分为5组，即正常对照组、模型组、电针组、化学遗传激活组以及化学遗传抑制+电针组，每组9只。所有干预均于模型构建完成后8周内实施。我们检测了大鼠的肥胖相关表型，包括体质量、Lee指数、24小时进食量及糖代谢参数。通过蛋白质印迹法（western blotting, WB）与实时荧光定量聚合酶链反应（real-time polymerase chain reaction, RT-qPCR）检测孤束核内GLP-1以及腹侧被盖区内酪氨酸羟化酶（tyrosine hydroxylase, TH）的蛋白与基因表达水平，并采用免疫荧光法观察二者的细胞定位。此外，通过高效液相色谱法（high-performance liquid chromatography, HPLC）检测腹侧被盖区的多巴胺含量。
研究结果：肥胖大鼠表现出显著的进食过多，同时伴随腹侧被盖区多巴胺神经元兴奋性升高以及胰岛素敏感性降低。经电针干预后，肥胖大鼠的孤束核GLP-1神经元兴奋性增强，腹侧被盖区多巴胺神经元兴奋性受到抑制，进食量减少，该效果与化学遗传激活组的结果相近。在实施电针干预的同时通过化学遗传学手段抑制GLP-1神经元时，电针激活GLP-1神经元以及抑制腹侧被盖区多巴胺神经元的作用被部分抵消，其改善肥胖与胰岛素敏感性的效果同样受到抑制。
研究结论：电针可有效激活孤束核内的GLP-1神经元，进而抑制腹侧被盖区的多巴胺表达，最终改善高脂饮食诱导肥胖大鼠的肥胖症状与胰岛素抵抗。